At the risk of over-simplification, the report says that there is still great uncertainty about the impacts of climate change. This means that we must be resilient to these changes and be prepared as far as possible. This is the second of three instalments of the IPPC's fifth assessment of climate change, and deals with the impact on society. The first part reveals an even more certainty that climate change is on-going as a result of emissions of greenhouse gases.

An important aspect of climate change is the growing evidence of more frequent extreme climate events all over the world.

Predictions of any sort are invariably different to what eventually happens, and this seems even more so with weather and climate.

YOUR LAWN

Are you lucky enough to have a lawn? Perhaps you view it as a nuisance requiring regular mowing. Some authorities regard it as this country's greatest contribution to the art of gardening, and there can surely be nothing to enhance the appearance of a garden more than a green velvet lawn.

It is around this date that the spring flush of new grass occurs. This year it has been extremely early, occurring at the end of March. It happens when the frosts of winter are largely finished, and lengthening hours of daylight with higher daytime temperatures allow grass to burst into life once again.

The South West of England has traditionally been mild enough to allow grass to grow throughout the winter. This allows cattle to remain out of doors, when further north the frequency of frost prevents the grass from growing for several months. The main problem for farmers in Cornwall and Devon is the heavy rainfall which causes cattle to tread the turf into muddy morasses.

If you are asked for our most important crop many would not say that it is grass – but it is. All cereal crops – wheat, barley, oats and now some maize for fodder – are varieties of grass.

Although not grown in Great Britain, rice, millet and sorghum are also varieties of grass.

LIVESTOCK

Some readers may not realise that all our livestock – cattle, sheep and pigs – depend fundamentally on grass for food. Sheep graze our hills and uplands, as well as some lowland areas where conditions are suitable, and they produced the wool which brought great prosperity to England in Medieval times. The Cotswold Hills have many villages which are built of the beautiful limestone which underlies these hills. They also have magnificent churches which clearly must have been very expensive to build. As you have guessed, they were financed out of the profits from the wool trade when wool was exported to the continent.

PAST APRIL WEATHER

18th 1850 A violent thunderstorm broke over Dublin, producing a tornado as well as gigantic hail stones.

19th 1849A depression moving eastwards along the English Channel, produced a great snowstorm across southern England. The snow drifted in the strong easterly winds producing deep drifts which even buried coaches.

20th 1893 Some very hot weather affected the country, with 28, 82.5F in London, as high pressure drew in warm air from the continent

21st 1695An influx of south westerly winds brought welcome rain which ended an exceptionally long, severe and snowy winter. It was reported to be the first rain for several months in the south east of England.

Winds from the north east and east had blown since 21st March, and also for most of the winter months. The winds were more variable for the next few months, but still from the north east at times. This was consistent with high pressure dominating the North Atlantic near Iceland.

This was the year that saw the greatest ever recorded extent of the Arctic ice which completely surrounded Iceland.

23rd 1908 30cm, 12ins of snow lay in parts of Norfolk and Suffolk. The next day 15cm, 6ins, lay at Epsom.

24th 1600 A deep snowfall was recorded in parts of England. Bear in mind that accurate records from that period are rare.

1850 A depression moved southwards over the North Sea, bringing a very cold Arctic airstream. It caused widespread snowfalls affecting the south and south-east worst of all. With trees already in leaf the snow caused a great deal of damage. Most of Kent and Wiltshire had 13cm, 5ins. In London there was an unbroken snow cover on the pavements – very rare even in mid-winter

I wrote about some of the characters in this game of particle physics, a few weeks ago – here are some more.

A pokeman is not a new app or game. It's the new quasiparticle, discovered in Germany. Now, I know you knew that – didn't you? It is also called a "quantum droplet".

They don't really exist as particles, but arise thanks to the complex motions within a material. They behave in a similar way to real particles, but can only exist inside solids. I'm glad we have cleared that up. Wait, there's more.

Dropletons are clusters of quasiparticles known as "electron holes" and electrons themselves. It is the result of interactions within the 3D lattice of atoms that make up a chunk of semiconducting material. They only exist for 25 trillionths of a second, which believe it or believe it not, is actually quite a long time for a quasiparticle!

I am so glad that I have managed to explain this to you so that there is a clear understanding of these simple matters. Fact is indeed stranger than fiction – on second thoughts, is there a difference?

GENGHIS KHAN

This almost legendary conquerer swept out of Central Asia to conquer much of Eastern Europe. However, when you examine the geographical background to the mongol hoards he led, a semi desert, or dry steppes environment is revealed. So the question arises how were they equipped to sweep westwards and leave an indelible trace on our history?

Climate change – at least for a time – seems likely to have been the driving force. Dendrochonological studies (tree rings), of trees from the normally arid central Asian steppes reveal that they had relatively wet weather in the early 1200s. This would have resulted in an abundant growth of grass. Mongol livestock would then have been healthy and plentiful for Genghis Khan's ambitions.

It is quite characteristic for semi-arid regions all over the world to have cyclical climates with wet rainy periods alternating with dry periods. The dry American west in Texas, Oklahoma, Kansas and Nebraska, has regularly undergone such spells. The Dust Bowl of the 1920s-30s was one such dry period. John Steinbeck's "Of Mice and Men" described the terrible effects on the farming community, which had established itself during one of the wetter spells a couple of decades earlier.

THE FIRST OIL REFINERY

I bet you think it was in America – well, it wasn't, it was in Scotland. James Young established the Scottish Oil Shale Industry at Bathgate, Scotland. He was able to extract 100 gallons of oil from each ton of oil shale at his oil refinery in 1850. He also invented the paraffin lamp and took out the patent for paraffin. That might not seem much, but up until then candles still dominated households, and what lamps there were relied on whale oil as a fuel. His paraffin lamps were only superceded in 1879 when Sir Joseph Swann, of Gateshead, (not Edison, who copied Swann's bulb) invented the incandescent electric light bulb and had the first house in the world to be lit by electricity.

EARLY FOLKLORE ABOUT WEATHER

As far as I am aware, Aristotle wrote his Meteorologica about 200 BC. He discussed the formation of rain, dew, rainbows and many other meteorological phenomena as though he was a modern scientist.

"... Some of the [water] vapour that is formed by day does not rise high because the ratio of the fire that is raising it to the water that is being raised is small. When this cools and descends at night it is called dew or hoar-frost. When the vapour is frozen before it has condensed to water again it is hoar-frost; and this appears in winter and is commoner in cold places. It is dew when the water has condensed into water and the heat is not so great as to dry up the moisture that has been raised, nor the cold sufficient (owing to the warmth of the climate or season) for the vapour to freeze. For dew is more commonly found when the season or the place is warm, whereas the opposite is the case with hoar-frost.

For obviously vapour is warmer than water, having still the fire that raised it: consequently more cold is needed to freeze it. Both dew and hoar-frost are found when the sky is clear and there is no wind. For the vapour could not be raised unless the sky were clear, and if a wind were blowing it could not condense ..."

Aristophanes in the 5th century BC wrote a comedy called "Clouds" in which there is an argument as to whether thunder was made by ZEUS, or was the result of a clash of clouds in a vortex of air.

The Roman Pliny wrote in the first century AD about sailing winds. "The coldest winds are those that ... blow from the North, and their neighbour Corus [NW]; these check the other winds and also drive away the clouds. The southwest and especially south are for Italy damp winds ...The northwest and southeast are dry, except where they are falling.

"The northeast and north are snow winds; the north brings hailstorms, and so does the northwest. The south winds are hot, the southeast and west warm; the latter are also drier than the east wind ... The healthiest of all is the north wind; the south is harmful ... Etesian winds usually cease at night and rise at eight o'clock in the morning; in Spain and in Asia they are east winds, on the Black Sea north, and in other regions south. But they also blow at midwinter ... but more gently and only for a few days. Two winds also change their nature with their geographical position; the south wind in Africa is fine and the northeast cloudy.

"The south wind causes larger waves than the northeast ... is more violent at night, while the northeast is more violent in the day. Easterly winds blow longer than westerly. North winds stop after an odd number of days."

Coming to more recent times the Venerable Bede also contributed his views, but it is unlikely that he based them on actual observations as he spent most of his time in a cell at Jarrow. Some consider that he derived his views from authors such as Theophrastus, Virgil and Pliny, so he was actually a bit of a plagiarist. The general medieval view which was sanctioned by the Pope and widely shared was once again based more on holy scriptures than common sense.

"It is a dogma of faith that demons can produce winds, storms and rain fire from heaven," wrote St Thomas Aquinas in the 13th century AD, and he was more enlightened than most !

SCIENTIFIC OBSERVATIONS

None of the weather wisdom of the ancients was based on precise measurement, it was all patient observations made over millennia, often tinged with religious imaginings. The first scientific instrument to measure an important aspect of the atmosphere and thus the weather, was the barometer.

In 1643, the Italian, Toricelli, who was amanuensis to blind Galileo, discovered that the atmosphere would support a column of mercury 30 inches high in a glass tube closed at one end, that had been filled with mercury and inverted with its open end below the surface of a container of mercury. The variations in height were the result of changes in atmospheric pressure.

Then along came the thermometer invented by Galileo to measure how much heat the air contained. The way was now open for accurate, precise measurements to be made and the correct physics of the atmosphere to be understood – no more gods, demons and a range of fantastic absurdities.